1. Field of the Invention
The present invention relates to a sheet handling apparatus, and more particularly to a sheet handling apparatus which stacks sheets ejected from an image forming apparatus set by set and carries out stapling, punching, binding etc. with respect to each set of sheets.
2. Description of Related Art
Recently, in the art of copying machines and printers, various types of sheet handling apparatuses (finishers) which staple, punch and/or bind sheets with images thereon have been developed.
With respect to such sheet handling apparatuses, there has been a type which distributes sets of sheets among a plurality of sheet trays arranged on different levels and carries out necessary processes with respect to the sets of sheets. However, providing a plurality of sheet trays on different levels causes problems of increasing the size of the apparatus and of complicating the sheet transport system.
Also, there has been another type which has a single sheet tray and carries out necessary processes with respect to a set of sheets stacked on the tray. This type can be downsized. However, transportation of a next set of sheets to the tray cannot be started until the previous set has been subjected to necessary processes and taken out of the tray. Accordingly, image forming operations must be commonly delayed, thereby lowering productivity.